Generally, container spouts could not be folded in so that the user inclined the container to drink the contents of the container.
U.S. Pat. No. 4,492,324 discloses a container with a bellows shaped foldable portion, but it is difficult to mold the bellows shaped foldable portion so that it cannot be in use commonly.
Further, it is a problem that when the inner pressure is applied to the container, the foldable portion is unfolded.